The present invention relates to a closure device for a convertible top, comprising a lateral roof frame, a hoop element, and a pivotable hook arranged on the lateral roof frame and which can be brought into engagement with the hoop element.
Convertible-vehicle construction has provided convertible tops in which the lateral roof-frame parts can be secured on a frame element of the vehicle, in particular on a rigid windshield frame, such that they can be released by means of movable closure hooks and hoop catches which correspond with the latter and are provided on the windshield frame. In the case of convertible tops, which open and close in an automated manner, these closure devices are provided with a separate drive.
Also known are folding/sliding tops in which a front end of a flexible fabric is secured on a front bow and the front bow is accommodated in lateral roof frames such that it can be moved in the longitudinal direction of the vehicle.
Solutions in which linear guides are provided in the front roof-frame segments are known in particular, a catch hook which is retained in a pivotable manner at the end of the roof-frame segments or else on drivable sliding elements, which slide in the linear guides, being provided by means of the sliding elements. The sliding elements are driven in an advantageous and cost-effective manner here by means of known driving cables which, on the one hand, can be favorably produced as mass-production components and, on the other hand, take up only a small amount of space and can be adapted easily and universally as drive means. A fundamental disadvantage of such driving-cable drives is the only limited loading capacity of the driving cables in respect of the force transmission. The closure between the roof frames of convertible tops or front bows of folding/sliding tops and a front frame of the vehicle, however, on account of the high wind forces acting on the convertible top, needs to be generously designed in respect of the retaining force. In addition, tensioning is usually introduced into the covering fabric of the convertible top as the roof-frame segments are secured on the windshield frame, this requiring additional forces for the closure movement. The above described solutions are generally beset by the problem of relatively large frictional forces occurring when sliding elements are used. On the whole, it proves to be the case that the driving forces necessary for closing the roof-frame segments on the windshield frame exceed the driving forces that can be transmitted by commercially available driving cables. Use has thus been made, in the construction of convertible tops, of solutions that provide the use of two parallel drive motors in order to increase the advancement force of the sliding elements. Alongside additional costs and structural outlay, this solution is also unsatisfactory in that, in the case of the prior-art designs with the additional driving force, the frictional losses also increase, with the result that it is possible to achieve a less than proportional improvement in the forces which can ultimately be applied to the closure hook.